May 14, 1999 WEST LAFAYETTE, Ind. -- Flower researcher Natalia Dudareva is on the scent of a mysterious disappearance. "Selective breeding has reduced flower scent to almost nothing," says Dudareva, a Purdue University assistant professor in the Department of Horticulture and Landscape Architecture. "Flowers are bred for color, size and shelf life without any attention to scent. Floral scent disappeared, and nobody knows why."
Dudareva is one of the few scientists in the world who is working to answer that question, and a few others, about this most appreciated -- but least understood -- plant characteristic.
Since arriving at Purdue in 1997, the native Russian has set up a laboratory with growth facilities. It's only the second floral scent lab in the United States working at the molecular level. The first was the one she left at the University of Michigan, where she and her colleagues had isolated three genes for enzymes that form volatile compounds, which combine to produce scent.
Volatile compounds are essential oils that evaporate in warm weather and combine in various proportions to produce distinctive odors that are identical among plants of the same variety. An orchid could produce about 100 different volatile compounds, while a snapdragon produces about seven to 10. While much has been done to analyze the composition of scent, we're just learning about the genes that produce the compounds and how they are given off.
While she appreciates the smell of fresh flowers, Dudareva says the real attraction for her is the chance to study this little-known aspect of plant biology. Plants use volatile compounds to repel and kill pests, to attract pollinators, and to communicate between cells and plants. Volatile compounds can be expressed in minute quantities that are impossible to work with individually, but they become more workable when combined as floral scent.
One compound, linool, is toxic to some insects. The same compound, though, allows moths to find the Clarkia plant, which has small pink flowers and depends on a nocturnal moth for pollination. Linool is a long-distance volatile compound; it travels great distances to attract pollinators. As a moth closes in, it fixes on a different short-distance compound to help it zero in on a specific flower.
Plants also use volatile compounds to warn other plants.
"There are known examples of plants that have been infected with a virus and have released a volatile compound that signals other plants to set up defenses against the virus," Dudareva says.
Once she understands how plants produce volatile compounds and what genes are involved, Dudareva says she hopes to be able to manipulate the genes to enhance the beneficial aspects of scent. "Of course, we'll also be able to produce lots of nice smelling flowers," she says.
She's also intrigued by the field of aromatherapy and the attempts to link health benefits with exposure to certain smells. If links can be established between scent and health effects, such as stress reduction, Dudareva knows that interest in her work will blossom.
"What if you could make yourself feel better simply by putting a vase of enhanced flowers on your desk?" Dudareva asks. "That would be better than taking a pill!"
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